I am getting the sitemap of just 3 pages with www and without it its 500 pages.. problem is google is not accepting sitemap without www.I am keeping options as default. I have tried this same tool many times before with www and it worked fine always.

Most of your sites pages are hard coded without the www prefix. Because these wil be seen as a different site they won't be included in the sitemap. Your only options are 1. change the links on your site to include the www prefix or 2. submit your site to Google without the www prefix and submit a sitemap with pages that don't include the www prefix